Surface photochemistry: The effect of surface modification on the singlet quenching of pyrene adsorbed on silica gel by 2-bromonaphthalene

Abstract Variation in the heat treatment of silica gel, and thus its degree of hydration, prior to the adsorption of pyrene and the quencher 2-bromonaphthalene (BN) onto the surface, influences the rate of quenching of pyrene fluorescence. The quenching rate is slow with dry silica gel whereas on dry silica gel treated with additives such as water or 1-decanol the rate is greater. Heat treatment causes changes in the number, nature and disposition of silanol groups on the gel surface, thereby influencing the mobilities of pyrene and BN and their diffusional quenching rates and the contribution to the total emission and ground state “dimers”.